Oklahoma's lawsuit contending a key part of President Barack Obama?s 2010 health-care reform legislation is blocked by the state's constitution should be thrown out, lawyers for the U.S. said in a court filing. "Oklahoma lacks standing to sue the federal government to deprive its residents of the benefits of federal law," U.S. Justice Department attorneys argued in papers filed yesterday in federal court in Muskogee, Oklahoma. State Attorney General Scott Pruitt, a Republican, filed the lawsuit in January 2011, about 10 months after the president signed into law the Patient Protection and Affordable Care Act that made the acquisition of basic health insurance mandatory for almost all Americans. That part of the law takes effect in 2014.